Quantitative, real time measurements of localized corrosion events

An electrochemical noise method, apparatus and system calculates parameters of interest related to corrosion rates of an electrically conductive article. The method involves placing a test electrode, a reference electrode, and an auxiliary electrode in an environment of interest; placing the test electrode under potentiostatic control regime for a potential scan; measuring the relationship of current v. potential (polarization resistance, Rp) of the test electrode relative to the reference electrode during a first period; switching from potentiostatic control to the open circuit potential (OCP) of the test electrode; monitoring the OCP of the test electrode during a second period; determining ΔI from the relationship Rp=ΔV/ΔI, where ΔV is measured over a second period of time; and calculating the localized corrosion from the measured potential and current data.